1. Field of the Invention
The present invention relates generally to an apparatus for transporting a sheet and, more particularly, to a sheet transporting apparatus provided with the function of transporting, for example, a sheet which is inserted one by one from the exterior by manual sheet insertion.
2. Related Background Art
An electronic copying machine 100 of the conventional type shown in FIG. 1 is arranged to transport a sheet inserted by manual sheet insertion in the following manner. A manual sheet insertion tray 101 is inclined to the outside, and a sheet-like transfer medium 102 is fed from the tray 101. The transfer medium 102 is transported by paper feed rollers 103 and 105 and registration rollers 106 and passed toward a drum 110 through the gap between transfer guides 107 and 109. When an image formed on a drum 110 is transferred to the transfer medium 102 as a toner image by means of a transfer charger 111, the transfer medium 102 is separated from the drum 110 by a separation charger 112. Then, the transfer medium 102 is transported over a transport section 113 to a fixing roller section 115, in which the toner image is fixed. The fixed transfer medium 102 is finally discharged to a discharge tray 116. During the above operation, the transfer medium 102 is transported in the same direction.
When a multiple image is to be formed, after the completion of fixation, the transfer medium 102 which has passed through the fixing section 115 is conducted toward a double-sided/multiple-copy sheet transporting path 119 by a medium deflecting plate 117. The transfer medium 102 passes over the path 119 and is again transported toward the drum 110 and the fixing roller section 115. When images are to be formed on the opposite surfaces of the transfer medium 102, the discharge rollers 120 are reversed while discharging the transfer medium 102. The transfer medium 102 is conducted by the medium deflecting plate 117 and is again transported toward the drum 110 over the transporting path 119.
However, the above-described arrangement involves a number of problems. For example, since the manual sheet insertion tray 101 is positioned on the right side of the electronic copying machine 100, an operator needs to incline the tray 101 to the right and set the transfer medium 102 thereon. It is therefore necessary to leave sufficient space on the right side of the copying machine 100, with the result that space efficiency is impaired by the installation of the copying machine 100.
Another problem is pointed out with respect to a conventional arrangement in which the transfer medium 102 is fed from the manual sheet insertion tray 101, provided on the front side of the electronic copying machine 100, in a direction substantially orthogonal to the double-sided/multiple-copy sheet transporting path 119. For example, such a conventional arrangement requires the provision of means for orthogonal transportation, means for positioning the transfer medium 102, means for switching the transport mechanism of the double-sided/multiple-copy sheet transporting path 119, and other associated parts. Accordingly, the copying machine 100 increases in height.
It has also been proposed to use an arrangement such as that shown in FIG. 2. As shown in FIG. 2, a manual sheet insertion tray projects to the right, and a sheet accommodating tray (cassette) is set in a bottom portion of the copying machine on the front side thereof. A double-sided/multiple-copy sheet transporting path is positioned above the sheet accommodating tray. However, this arrangement still presents problems similar to those described above.